U.S. patent application number 16/315795 was filed with the patent office on 2019-10-03 for tilting forecarriage of a motor vehicle and a related motor vehicle.
The applicant listed for this patent is PIAGGIO & C. S.P.A.. Invention is credited to Andrea RAFFAELLI, Alberto VIANELLO.
Application Number | 20190300095 16/315795 |
Document ID | / |
Family ID | 57610066 |
Filed Date | 2019-10-03 |
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United States Patent
Application |
20190300095 |
Kind Code |
A1 |
RAFFAELLI; Andrea ; et
al. |
October 3, 2019 |
Tilting forecarriage of a motor vehicle and a related motor
vehicle
Abstract
Motor vehicle forecarriage (8) comprising a forecarriage frame
(16), a pair of front wheels (10', 10'') kinematically connected to
the forecarriage frame (16) by means of an articulated
quadrilateral (20), said articulated quadrilateral (20) comprising
a pair of cross members (24', 24''), hinged to the forecarriage
frame (16) at middle hinges (28), said cross members (24', 24'')
being connected to each other at opposite transverse ends (40, 44),
by means of uprights (48, 48', 48'') pivoted to said transverse
ends (40, 44) at side hinges (52), the cross members (24', 24'')
and the uprights (48), the tilting support structure (72) being
hinged to the articulated quadrilateral (20) by means of steering
hinges (76) a guide wheel (88) connected to the rotation pin (68)
of front wheel (10', 10'') at a special wheel attachment (94), a
support bracket (92) hinged to the articulated quadrilateral (20)
by means of said steering hinges (76), the guide wheel (88) being
in turn hinged to the support bracket (92) at opposite upper and
lower axial ends (96, 98).
Inventors: |
RAFFAELLI; Andrea;
(Pontedera, IT) ; VIANELLO; Alberto; (Pontedera,
IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PIAGGIO & C. S.P.A. |
Pontedera |
|
IT |
|
|
Family ID: |
57610066 |
Appl. No.: |
16/315795 |
Filed: |
June 29, 2017 |
PCT Filed: |
June 29, 2017 |
PCT NO: |
PCT/IB2017/053923 |
371 Date: |
January 7, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60G 11/10 20130101;
B62K 5/10 20130101; B60G 2300/45 20130101; B60G 2300/122 20130101;
B62K 5/027 20130101; B62D 9/02 20130101; B60G 2200/44 20130101;
B62K 5/05 20130101; B62K 5/06 20130101; B62K 5/08 20130101; B60G
2202/117 20130101; B62K 2202/00 20130101 |
International
Class: |
B62K 5/10 20060101
B62K005/10; B62K 5/06 20060101 B62K005/06; B62K 5/08 20060101
B62K005/08; B62K 5/027 20060101 B62K005/027; B62K 5/05 20060101
B62K005/05 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 8, 2016 |
IT |
102016000071697 |
Claims
1. Motor vehicle forecarriage comprising a forecarriage frame, a
pair of front wheels kinematically connected to the forecarriage
frame by means of an articulated quadrilateral, said articulated
quadrilateral comprising a pair of cross members, hinged to the
forecarriage frame at middle hinges, said cross members being
connected to each other, at opposite transverse ends, by means of
uprights pivoted to said transverse ends at side hinges, each
upright extending from an upper end to a lower end, the upper end
being turned towards the upper cross member and the lower end being
turned towards the lower cross member, the cross members and the
uprights defining the articulated quadrilateral (20). wherein the
forecarriage comprises, at each front wheel, a tilting support
structure mechanically connected to a rotation pin of each front
wheel so as to rotatably support the front wheel around a related
rotation axis, the tilting support structure being hinged to the
articulated quadrilateral by means of steering hinges arranged at
the upper ends and lower ends of each upright, said steering hinges
defining respective steering axes of the wheels parallel to each
other, wherein the tilting support structure comprises a guide
wheel connected to the rotation pin of front wheel at a special
wheel attachment, a support bracket hinged to the articulated
quadrilateral by means of said steering hinges, the guide wheel
being in turn hinged to the support bracket at opposite upper and
lower axial ends, by means of two tilting hinges that define
respective tilting axes and that form a roto-translational
connection between the guide wheel and the support bracket, wherein
the tilting support structure comprises a damper element and/or an
elastic element to control the tilting movement, wherein the
elastic element connects the guide wheel and the support bracket to
each other.
2. Motor vehicle forecarriage according to claim 1, wherein the
elastic element is mounted cantilevered between the support bracket
and an axial end of the guide wheel.
3. Motor vehicle forecarriage according to claim 1, wherein said
elastic element is a leaf spring respectively associated to the
guide wheel and the support bracket at a first and a second tilting
hinge.
4. Motor vehicle forecarriage according to claim 3, wherein said
first and second tilting hinge are elastic deformation hinges.
5. Motor vehicle forecarriage according to claim 1, wherein the
tilting support structure comprises a connecting rod doubly hinged
to the support bracket and the guide wheel at a first and a second
tilting hinge.
6. Motor vehicle forecarriage according to claim 5, wherein the
elastic element is mounted cantilevered between the guide wheel and
an anchorage of said connecting rod.
7. Motor vehicle forecarriage according to claim 5, wherein said
elastic element leaf is a coil spring.
8. Motor vehicle forecarriage according to claim 5, wherein the
elastic element is connected cantilevered between the guide wheel
and the support bracket, parallel with respect to the connecting
rod.
9. Motor vehicle forecarriage according to claim 8, wherein said
elastic element is a leaf spring.
10. Motor vehicle forecarriage according to claim 1, wherein said
guide wheel is a rectilinear guide which comprises the damper
element.
11. Motor vehicle forecarriage according to claim 1, wherein the
guide wheel comprises a stem, which houses the damper element, and
a case, fitted coaxially to the stem, and translatable with respect
to the stem, the case supporting the wheel stub axle, the damper
element being placed between the case and the stem.
12. Motor vehicle forecarriage according to claim 1, wherein the
guide wheel, the support bracket and the tilting hinges delimit a
perimetrically closed tilting support structure.
13. Motor vehicle forecarriage according to claim 12, wherein the
rotation pin of each wheel is positioned inside said perimetrically
closed tilting support structure, and/or the side hinges and the
respective upright are positioned inside said perimetrically closed
tilting support structure.
14. Motor vehicle forecarriage according to claim 1, wherein the
tilting support structure comprises an end hinged to the support
bracket and to the guide wheel at a third tilting hinge.
15. Motor vehicle forecarriage (8) according to claim 1, wherein
said tilting hinges are hinged to the support bracket and the guide
wheel at the tilting axes perpendicular to a centerline plane of
each wheel.
16. Motor vehicle forecarriage according to claim 1, wherein said
tilting hinges are hinged to the support bracket and the guide
wheel at the tilting axes perpendicular to the steering axes
defined by said steering hinges.
17. Motor vehicle forecarriage according to claim 1, wherein said
tilting support structure is entirely contained within a volume
delimited by a rim of each wheel, wherein said volume is facing
with respect to a centerline plane of the forecarriage passing
through said middle hinges.
18. Motor vehicle forecarriage according to claim 1, wherein the
transverse ends of the upper and lower cross members are partially
housed in transverse seats formed in said uprights.
19. Motor vehicle forecarriage according to claim 1, wherein to
each guide wheel are fixed braking means of the corresponding
wheel.
20. Motor vehicle forecarriage according to claim 1, wherein to
said support brackets are connected steering tie-rods kinematically
connected to an associable handlebar of the motor vehicle.
21. Motor vehicle forecarriage according to of the claim 1, wherein
the middle and side hinges are parallel to each other and are
oriented so that, with respect to a projection plane passing
through said middle hinges, the steering axes identify, with the
axes of the middle hinge and side hinge, an angle said angle
.alpha. being between 80 and 120 degrees and.
22. Motor vehicle forecarriage according to claim 1, wherein the
hinges are parallel to each other and orthogonal to said steering
axes so that, with respect to a projection plane passing through
said middle hinges the steering axes identify with the axes of the
middle hinge and side hinge, an angle of 90 degrees.
23. Motor vehicle forecarriage according to claim 1, wherein the
steering axes, with respect to a projection plane passing through
said middle hinges, are inclined by a steering angle between 4 and
20 degrees with respect to a vertical direction, perpendicular to
the ground.
24. Motor vehicle forecarriage according to claim 1, wherein the
middle and side hinges are inclined according to the axes of the
middle hinge and side hinge parallel to the ground, i.e.,
perpendicular to a vertical direction perpendicular to the
ground.
25. Motor vehicle forecarriage according to claim 1, wherein said
middle hinges and side hinges are oriented according to the axes of
the middle hinge and side hinge parallel to each other.
26. Motor vehicle having a drive wheel at the rear axle and a
forecarriage according to claim 1.
27. Motor vehicle according to claim 26, wherein the motor vehicle
comprises two rear drive wheels at the rear axle.
Description
SCOPE
[0001] The present invention concerns a tilting forecarriage of a
motor vehicle and a related tilting motor vehicle.
STATE OF THE ART
[0002] As is well known, there are in the art three-wheeled
vehicles with a rear drive wheel and two steering and tilting, i.e.
rolling or leaning, front wheels.
[0003] The rear wheel is therefore intended to provide the driving
torque and therefore to allow traction, while the paired front
wheels have the purpose of providing the directionality of the
vehicle.
[0004] The use of two front wheels, instead of two rear wheels,
avoids the use of a differential for the transmission of the
torque. This results in a reduction in costs and weight on the rear
axle.
[0005] The paired wheels on the forecarriage, in addition to
steering, can tilt and roll: in this way, unlike three-wheeled
vehicles with two wheels at the rear, vehicles with two wheels on
the forecarriage are similar to a real motorcycle give that, Just
like a motorcycle, the vehicle is able to lean into a curve.
[0006] With respect to a motor vehicle with only two wheels, such
vehicles with two paired wheels on the forecarriage have greater
stability provided by the double support on the ground of the front
wheels, similar to that provided by a car.
[0007] The front wheels are kinematically connected to each other
by means of kinematic systems which ensure that the same will roll
and/or steer synchronously and symmetrically, for example, via the
interposition of articulated quadrilaterals.
[0008] With regard to the steering angle of the front wheels, it is
also possible to provide different steering angles between the
front wheels, for example, if an automobile-type steering wheel is
used, with the outer wheel remaining more open in the curve.
[0009] Tilting three-wheeled motor vehicles are therefore designed
to provide the user with the maneuverability of a two-wheeled
motorcycle and, at the same time, the stability and safety of a
four-wheeled vehicle.
[0010] In fact, the two predetermined objectives are antithetical,
given that greater stability implies the presence of additional
elements with respect to a two-wheeled motor vehicle (such as, for
example, the third wheel and its kinematic systems), which
inevitably add weight to the vehicle's structure.
[0011] Moreover, the presence of `only` three wheels cannot
necessarily guarantee the stability and road-holding ability of a
four-wheeled vehicle.
[0012] Therefore, it is essential to develop a three-wheeled
vehicle that can withstand these antithetical targets while at the
same time ensuring stability and ease of handling, as well as
reliability and low costs.
[0013] To achieve these objects, a specific geometry of the front
portion of the frame, or forecarriage, must be developed to support
the front wheels in their steering and rolling or tilting
movement.
PRESENTATION OF THE INVENTION
[0014] To solve the aforementioned problems, a number of
three-wheeled vehicle solutions have been adopted in the art, two
of which are at the forecarriage.
[0015] Such solutions known in the art fail to optimize the need
for stability and maneuverability described above.
[0016] The need is therefore perceived to resolve the drawbacks and
limitations cited with reference to the known art.
[0017] This requirement is satisfied by a motor vehicle
forecarriage according to claim 1 and a motor vehicle according to
claim 26.
DESCRIPTION OF THE FIGURES
[0018] Further features and advantages of the present invention
will become more understandable from the following description of
its preferred and non-limiting embodiments, wherein:
[0019] FIG. 1 is a partial perspective view of a motor vehicle
according to an embodiment of the present invention;
[0020] FIG. 2 is a perspective view of the detail II of a
forecarriage of the motor vehicle of FIG. 1;
[0021] FIG. 3 is a side view of the detail of FIG. 2, from the side
of the arrow III of FIG. 2;
[0022] FIG. 4 is a plan view of the detail of FIG. 2, from the side
of the arrow IV of FIG. 2;
[0023] FIG. 5 is a side view of the detail of FIG. 2, from the side
of the arrow V of FIG. 2;
[0024] FIG. 6 is a partial perspective view of a motor vehicle
according to a further embodiment of the present invention;
[0025] FIG. 7 is a perspective view of the detail VII of a
forecarriage of the motor vehicle of FIG. 6;
[0026] FIG. 8 is a side view of the detail of FIG. 7, from the side
of the arrow VIII of FIG. 7;
[0027] FIG. 9 is a plan view of the detail of FIG. 7, from the side
of the arrow IX of FIG. 7;
[0028] FIG. 10 is a side view of the detail of FIG. 7, from the
side of the arrow X of FIG. 7;
[0029] FIG. 11 is a partial perspective view of a motor vehicle
according to a further embodiment of the present invention;
[0030] FIG. 12 is a perspective view of the detail XII of a
forecarriage of the motor vehicle of FIG. 11;
[0031] FIG. 13 is a side view of the detail of FIG. 12, from the
side of the arrow XIII of FIG. 12;
[0032] FIG. 14 is a plan view of the detail of FIG. 12, from the
side of the arrow XIV of FIG. 12;
[0033] FIG. 15 is a side view of the detail of FIG. 12, from the
side of the arrow XV of FIG. 12.
[0034] The elements or parts of elements in common between the
embodiments described hereinafter will be indicated with the same
numerical references.
DETAILED DESCRIPTION
[0035] With reference to the aforementioned figures, a total
schematic view of a motor vehicle according to the present
invention is collectively indicated at 4.
[0036] For the purposes of the present invention, it should be
noted that the term `motor vehicle` is to be considered in the
broad sense, including any motorcycle having at least three wheels,
i.e., two front wheels, as better described below, and at least one
rear wheel. Thus, so-called quadricycles are also included in the
definition of a motor vehicle, having two wheels on the
forecarriage and two wheels on the rear axle.
[0037] The motor vehicle 4 comprises a frame 6 extending from a
forecarriage 8 which supports at least two front wheels 10,10',10''
to a rear axle supporting one or more rear wheels (not shown).
[0038] It is possible to distinguish a left front wheel 10' and a
right front wheel 10'' wherein the definition of the left and right
wheel 10',10'' is purely conventional and is intended with respect
to a driver of the vehicle. Said wheels are, therefore, arranged to
the left and to the right of a centerline plane M-M of the motor
vehicle, relative to the observation point of a driver of the
same.
[0039] In the following description, and also in the figures,
reference will be made to specular or symmetrical elements of the
forecarriage relative to said centerline plane M-M, using the marks
' and '' to indicate respectively the left and right components
respectively of the forecarriage, with respect to a driver's
observation point when driving the same.
[0040] For the purposes of the present invention, the frame 6 of
the motor vehicle may be of any shape and size and may, for
example, be of the trellis-type, box-type, single- or
double-cradle, and so on.
[0041] The frame 6 of the motor vehicle may be in one piece or in
several parts; for example, the frame 6 of the motor vehicle
interconnects with a rear axle frame which may comprise a rear
swingarm (not shown) that supports one or more of the rear drive
wheels.
[0042] Said swingarm may be connected to the frame 6 by direct
hinging, or by interposing intermediate levers and/or frames.
[0043] The forecarriage of the motor vehicle 8 comprises a
forecarriage frame 16 and a pair of front wheels 10 kinematically
connected to the forecarriage frame 16 by an articulated
quadrilateral 20.
[0044] The articulated quadrilateral 20 comprises a pair of cross
members 24, hinged to the forecarriage frame 16 at the middle
hinges 28.
[0045] The concept of an articulated quadrilateral must be
considered in the broad sense; in other words, a structure with at
least four sides suitable to allow the tilting movement of the
forecarriage and therefore of the entire vehicle. The term
`articulated quadrilateral` is also intended to mean a structure
having a greater number of sides and/or parts kinematically
equivalent to an articulated quadrilateral. In addition, the
present invention also covers an forecarriage solution comprising
two or more articulated quadrilaterals suitable for producing the
said tilting kinematics.
[0046] The middle hinges 28 define middle hinge axes W-W parallel
to each other.
[0047] For example, said middle hinges 28 engage with a front beam
32, which straddles a centerline plane MM passing through a
longitudinal direction X-X or the driving direction of the motor
vehicle.
[0048] For example, a steering mechanism, connected to a handlebar
(not shown) of the motor vehicle 4, is pivoted on a steering column
rotatably inserted in a sleeve of frame 6 of the motor vehicle 4,
in a known manner.
[0049] The cross members 24 extend along a predominantly transverse
direction Y-Y between opposing transverse ends 40,44.
[0050] In particular, the cross members 24 are connected to each
other at said opposing transverse ends 40,44 by means of uprights
48 pivoted to said transverse ends 40,44 at the side hinges 52.
[0051] In one embodiment, the cross members 24,24',24'' are mounted
cantilevered with respect to the front beam 32.
[0052] The cross members 24 and the uprights 48 define said
articulated quadrilateral 20. In particular, the quadrilateral 20
comprises two cross members 24, i.e. a top cross member 24' and a
lower cross member 24'', wherein the upper cross member 24' faces
the part of the associable handlebar and the lower cross member
24'' faces the ground supporting the motor vehicle 4.
[0053] The cross members 24', 24'' are not necessarily equal to
each other in shape, material and size; each cross member 24 may be
made in one piece or in two or more mechanically associated parts,
e.g. by welding, bolts, rivets and the like.
[0054] The uprights 48 are two, in particular a left upright 48'
and a right upright 48''.
[0055] The definition of the left and right upright 48', 48'' is
purely conventional and refers to a driver of a vehicle. Said left
and right uprights 48',48'' are arranged to the left and to the
right of a centerline plane M-M of the motor vehicle, relative to
the observation point of a driver of the same.
[0056] The side hinges 52 are parallel to each other and define the
respective axes of the side hinges Z-Z.
[0057] Preferably, said middle 28 and side 52 hinges are oriented
according to middle W-W and side Z-Z hinge axes parallel to each
other.
[0058] The left and right uprights 48',48'' support rotatably the
left and right front wheels 10',10'' respectively, around
respective steering axes S'-S',S''-S''. Said steering axes
S'-S',S''-S'' are parallel to each other.
[0059] Each upright 48 extends from an upper end 60 to a lower end
64.
[0060] The upper end 60 is directed toward the upper cross member
24' and the lower end 64 directed toward the lower cross member
24''. Each front wheel comprises a stub axle 56 of a front wheel
10.
[0061] According to one embodiment, each stub axle 56 is
mechanically connected to a rotation pin 68 of a front wheel 10 so
as to rotatably support the front wheel 10 around a related
rotation axis R-R.
[0062] Preferably, each rotation pin 68 of the front wheel 10 is
between the upper end 60 and the lower end 64 of the corresponding
upright 48 of the articulated quadrilateral 20.
[0063] According to one possible embodiment, the hinges 28 and 52
are parallel to each other and also orthogonal to said steering
axes S'-S',S''-S''. In other words, according to one embodiment,
with respect to a projection plane P passing through said middle
hinges 28, the steering axes S'-S',S''-S'' identify, with the
middle W-W and side Z-Z hinge axes, an angle .alpha. of 90
degrees.
[0064] According to possible embodiments, said angle .alpha. is
between 80 and 120 degrees, and, preferably, said angle .alpha. is
between 90 and 110 degrees; even more preferably said angle .alpha.
is 100 degrees.
[0065] The steering axes SY-S',S'',S'', relative to said projection
plane P, may be inclined at a steering angle .beta. between 4 and
20 degrees and more preferably between 8 and 16 degrees relative to
a vertical direction N-N, perpendicular to the ground.
[0066] According to further embodiments, it is also possible to
provide that the hinges 28 and 52 are inclined according to middle
W-W and side Z-Z hinge axes parallel to the ground, i.e.
perpendicular to said vertical direction N-N relative to said
projection plane P: in such configuration said angle .beta. is 0
degrees.
[0067] Also, as seen, it is possible to provide that the hinges 28
and 52 are not perpendicular to the steering axes S'-S',S''-S'': in
fact, as described above, said angle .alpha., identified between
the steering axes S'-S',S''-S'' and the middle W-W and side Z-Z
hinge axes relative to a projection plane P passing through said
middle hinges 28, may be between 80 and 120 degrees.
[0068] The parallelism to the ground of the middle W-W and side Z-Z
hinge axes causes, in the rolling motion, the inner wheel with
respect to the curve to rise up almost vertically with the double
advantage of making the rolling motion of the wheel decoupled from
the horizontal braking forces (transmitted by the ground) and of
occupying less space toward the motor vehicle hull.
[0069] It should be noted that by tilting the middle W-W and side
Z-Z hinge axes with respect to the S'-S',S''-S'' steering axes, so
that, in static states of rest, said middle and side hinge axes
W-W, Z-Z are not parallel to the ground, it is obtained that in
braking conditions, and therefore compression of the suspensions of
the front wheels 10',10'' described below, the same middle and side
hinge axes W-W, Z-Z are inclined, assuming substantial parallelism
with the ground. For example, it occurs that, in static states, the
middle and side hinge axes W-W, Z-Z define a non-zero angle .beta.
with the horizontal direction (which coincides with the angle
formed with the vertical direction, which is normal in the
horizontal direction); in braking conditions and in maximum
compression such angle tends to be canceled.
[0070] When, in braking, the middle W-W and side Z-Z hinge axes
being substantially parallel to the ground, wheel slip is avoided,
given that the braking forces, horizontal and therefore parallel to
the ground, do not give components along the excursive movement of
the wheels, which ends up virtually orthogonal to the ground, that
is, vertical.
[0071] It should be noted that the upper 60 and lower 64 ends of
the uprights 48',48'' are placed above and below the rotation pin
68 of the respective front wheels 10',10'' and not completely above
it, as is the case in the solutions of the known art.
[0072] In other words, each rotation pin 68 of the front wheel
10',10'' is between the upper end 60 and the lower end 64 of the
corresponding upright 48 of the articulated quadrilateral 20.
[0073] This implies that the stiffness of the connection between
each wheel 10',10'' and the articulated quadrilateral, comprising
the suspension, is an order of magnitude stiffer than the
aforementioned solutions of the prior art, helping to make more
remote the possibility that an alternate resonance of the wheels
10',10'' may occur due to braking forces or an asymmetrical impact.
Therefore, the present invention generally contributes to providing
a vehicle that is light but also safe and precise, and transmits to
the driver a sense of safety in the forecarriage, as it does not
cause the user to feel vibrations or shaking in the handlebar.
[0074] Moreover, the positioning of the upper and lower cross
members 24', 24'' of the articulated quadrilateral near the
vertical clearance of the wheels allows the center of gravity of
the front axle, and therefore the vehicle, to be moved downwards,
improving the dynamic behavior of the vehicle.
[0075] Advantageously, the forecarriage 8 comprises, at each front
wheel 10',10'', a tilting support structure 72 for a stub axle 56
of each front wheel 10',10'' mechanically connected to a rotation
pin 68 of each front wheel 10',10'' so as to rotatably support the
front wheel 10',10'' around a respective rotation axis R-R,
R'-R',
[0076] R''-R''.
[0077] Advantageously, said tilting support structure 72 being
hinged to the articulated quadrilateral 20 by means of steering
hinges 76 arranged at the upper ends 60 and lower ends 64 of each
upright 48',48'', said steering hinges defining respective steering
axes S'-S', S''-S'' of the wheels 10',10'' parallel to each
other.
[0078] Preferably, the steering axes S'-S',S'',S'' coincide with
the axes of symmetry of said uprights 48', 48'', respectively.
[0079] Each wheel 10',10'' comprises a centerline plane of the
wheel R'-R', R'' R'', wherein said centerline plane of the wheel
R'-R',R'',R'' preferably passes through the steering axis
S'-S',S'',S'' of each front wheel 10',10''. In a further
embodiment, there is provided a transverse offset or cantilever
between each steering axis S'-S',S''S'' and the related centerline
plane of the wheel R'-R', R''-R''. Such transverse cantilever is
between 0 and 2 cm, more preferably between 0 and 1 cm, and even
more preferably said transverse cantilever is 0.7 cm.
[0080] Preferably, said tilting support structure 72 is entirely
contained within a volume 80 delimited by a rim 84 of each wheel
10',10''.
[0081] Preferably, said volume 80 faces a centerline plane M-M of
the forecarriage 8 passing through said middle hinges 28. In other
words, the stub axles 56 are turned inward i.e. toward the
centerline plane M-M of the motor vehicle, and the related
components associated with the stub axle 56 are not directly
visible to an external observer.
[0082] According to a preferred embodiment, said tilting support
structure 72 comprises a guide wheel 88 connected to said stub axle
56 of the front wheel 10',10'' and a support bracket 92 hinged to
the articulated quadrilateral 20 by means of said steering hinges
76.
[0083] The guide wheel 88 is connected to the rotation pin and
rotatably supports said rotation pin 68 of the corresponding wheel
10',10'' at a specific wheel attachment 94.
[0084] The guide wheel 88 extends between opposite upper and lower
axial ends 96,98; preferably, at said opposite axial ends 96,98,
the guide wheel 88 is mechanically connected to connecting elements
on the frame.
[0085] For example, the guide wheel 88 is in turn hinged to the
support bracket 92 at opposite upper and lower axial ends 96,98 of
the guide wheel 88 by means of at least two tilting hinges 100 that
define respective tilting axes B-B and that realize a
roto-translational connection between the guide wheel 88 and the
support bracket 92. According to a possible embodiment, the guide
wheel 88 and the support bracket 92, as a whole, are mutually
connected by means of three tilting hinges 100 that define
respective tilting axes B-B, as better explained in the
following.
[0086] Preferably, the guide wheel 88, the support bracket and the
tilting hinges 100 delimit a perimetrically closed tilting support
structure 72.
[0087] `Perimetrically closed structure` is intended to mean that
the projections of the guide wheel 88 of the support bracket 92 and
the tilting hinges 100 on the centerline plane of the wheel
R'-R',R'',R'' define a closed polyline, i.e. having a closed
perimeter.
[0088] Preferably, the rotation pin 68 of each wheel 10',10'' is
positioned inside said perimetrically closed tilting support
structure 72, and/or the side hinges 52 and the respective upright
48 are positioned inside said perimetrically closed tilting support
structure 72.
[0089] Advantageously, the tilting support structure 72 comprises a
damper element 101 and/or an elastic element 102 to control the
tilting movement, wherein the elastic element 102 connects the
guide wheel 88 and the support bracket 92 to each other.
[0090] According to one embodiment, the elastic element 102 is
mounted cantilevered between the support bracket 92 and an axial
end 96,98 of the guide wheel 88.
[0091] According to one possible embodiment, said elastic element
102 is a leaf spring 103 respectively associated to the guide wheel
88 and the support bracket 92 at a first and a second tilting hinge
105,106.
[0092] For example, said first and second tilting hinges 105,106
may be elastic deformation hinges.
[0093] In other words, it is possible to fasten at least one end of
the leaf spring 103 so that, due to the elasticity of the spring,
this may flex elastically to form an elastic hinge.
[0094] According to one possible embodiment, the tilting support
structure 72 comprises a connecting rod 104 doubly hinged to the
support bracket 92 and to the guide wheel 88 at a first and a
second tilting hinge 105,106.
[0095] According to one possible embodiment, the elastic element
102 is mounted cantilevered between the guide wheel 88 and an
anchor 105 on the connecting rod 104.
[0096] For example, said elastic element 102 is a coil spring. Said
coil spring may be a steady or variable pitch spring so as to
suitably vary the elastic force as a function of the displacement
kinematics of the tilting support structure 72, and in particular
depending on the rotation of the connecting rod 104.
[0097] According to a further possible embodiment, the elastic
element 102 is connected cantilevered between the guide wheel 88
and the support bracket 92, parallel to the connecting rod 104.
[0098] For example, said elastic element 102 is a leaf spring
103.
[0099] The guide wheel 88 is a straight guide comprising the damper
element 101. This straight guide wheel 88 defines an agitation axis
T-T for each wheel 10',10''.
[0100] According to one embodiment, the guide wheel 88 comprises a
stem 124 which houses the damper element 101 and a case 126,
coaxially fitted flush with the stem 124 and translatable with
respect to the stem 124, the case 126 supporting the stub axle 56
of the corresponding wheel 10',10'' and being elastically affected
by the spring 120.
[0101] According to one possible embodiment, the tilting support
structure 72 comprises an end 128 hinged to the support bracket 92
and to the guide wheel 88 at a third tilting hinge 110. The first,
the second and the third tilting hinge 105,106,110, as a whole,
define respective hinge axes B-B and realize a roto-translational
connection between the guide wheel 88 and the support bracket
92.
[0102] According to one embodiment, the tilting hinges
100,105,106,110 are hinged to the support bracket 92 and to the
guide wheel 88 at the tilting axes B-B perpendicular to a
centerline plane R'-R', R''-R'' of each wheel 10',10''.
[0103] According to one embodiment, the tilting hinges
100,105,106,110 are hinged to the support bracket 92 and the guide
wheel 88 at the tilting axes B-B perpendicular to the steering axes
S'-S', S''-S'' defined by said steering hinges 76.
[0104] Preferably, the transverse ends 40,44 of the upper and lower
cross members 24',24'' of the articulated quadrilateral 20 are at
least partially housed inside transverse seats 152 formed within
said uprights 48', 48''.
[0105] Preferably, each guide wheel 88 is fitted with braking means
154 of the corresponding wheel 10',10''.
[0106] For example, said braking means 154 may comprise a disc
brake caliper. For the purposes of the present invention, braking
means 154 may be of any type; preferably, said braking means 154
are positioned and sized so as to enter within the volume 80
delimited by the rim 84 of each wheel 10',10''.
[0107] Preferably said guide wheel 88 comprises special eyelets 155
to allow the braking means 154 to be attached to the guide wheel
88.
[0108] Preferably, said support bracket 92 is connected to steering
tie-rods 156 kinematically connected to an associable handlebar of
the motor vehicle. For example, steering tie-rods 156 may be
connected to each support bracket 92 by interposing hinges or
spherical joints 160.
[0109] As mentioned above, the motor vehicle 4 according to the
present invention comprises at least one rear drive wheel;
according to one possible embodiment, the motor vehicle comprises
two rear drive wheels on the rear axle.
[0110] For example, in the embodiment wherein the motor vehicle is
a quadricycle, the rear drive wheels on the rear axle are connected
to each other and to a rear axle frame by means of an articulated
quadrilateral 20 as described above with respect to the front
wheels 10',10''.
[0111] According to a possible embodiment, the motor vehicle
forecarriage 8 comprises a forecarriage frame 16, a pair of front
wheels 10', 10'' kinematically connected to the forecarriage frame
16 by means of an articulated quadrilateral 20, said articulated
quadrilateral 20 comprising a pair of cross members 24', 24'',
hinged to the forecarriage frame 16 at middle hinges 28, [0112]
said cross members 24', 24'' being connected to each other, at
opposite transverse ends 40, 44, by means of uprights 48, 48', 48''
pivoted to said transverse ends 40, 44 at side hinges 52, each
upright 48', 48'' extending from an upper end 60 to a lower end 64,
the upper end 60 being turned towards the upper cross member 24'
and the lower end 64 being turned towards the lower cross member
24'', [0113] the cross members 24', 24'' and the uprights 48
defining the articulated quadrilateral 20, characterized in that
the forecarriage 8 comprises, at each front wheel 10', 10'', a
tilting support structure 72 for a stub axle 56 of each front wheel
10', 10'' mechanically connected to a rotation pin 68 of a front
wheel 10', 10'' so as to rotatably support the front wheel 10',
10'' around a related rotation axis R'-R', R''-R'', [0114] the
tilting support structure 72 being hinged to the articulated
quadrilateral 20 by means of steering hinges 76 arranged at the
upper ends 60 and lower ends 64 of each upright 48', 48'', said
steering hinges defining respective steering axes S'-S', S''-S'' of
the wheels 10', 10'' parallel to each other, wherein the tilting
support structure 72 comprises [0115] a guide wheel 88 connected to
the rotation pin 68 of front wheel 10', 10'' at a special wheel
attachment 94, [0116] a support bracket 92 hinged to the
articulated quadrilateral 20 by means of said steering hinges 76,
[0117] the guide wheel 88 being in turn hinged to the support
bracket 92 at opposite upper and lower axial ends 96, 98, by means
of at least three tilting hinges 100, 105, 106, 110 that define
respective tilting axes B-B and that form a roto-translational
connection between the guide wheel 88 and the support bracket 92,
wherein the tilting support structure 72 comprises a damper element
101 and/or an elastic element 102 to control the tilting movement,
wherein the elastic element 102 connects the guide wheel 88 and the
support bracket 92 to each other.
[0118] As may be appreciated from the foregoing, the present
invention overcomes the disadvantages of the prior art.
[0119] Advantageously, the present invention enhances the dynamic
behavior of the vehicle with respect to the solutions of the known
art.
[0120] In fact, the particular arrangement and architecture of the
front wheel support allows to significantly move back the center of
instantaneous rotation of the front wheels relative to the
longitudinal direction.
[0121] In this way, better control of suspension dive is obtained,
comparable to that obtainable by the use of a traditional-type fork
with telescopic stems. In other words, the suspension dive is
uniform and progressive, and the forecarriage of the motor vehicle
transmits to the driver a feeling of stability and confidence.
[0122] Moreover, the tilting-type mounting of the support structure
of the front wheels prevents the same suspension, comprising a
spring and shock absorber housed in the guide wheel, from being
stressed to flexure: in this way, the relative sliding between the
stem and the case of the suspension is facilitated and jamming
phenomena are avoided. It is possible, therefore, to avoid
oversizing the suspension to overcome such flexure and jamming of
the suspension given that, due to the tilting, the suspension may
accommodate the shaking movement of the wheel with respect to the
frame by tilting without flexing and therefore without jamming.
[0123] This effect is even more evident in the case of braking
because the significant forces in play do not tend to flex the
suspension, which may tilt, extending and compressing freely, so as
to duplicate the roughness of the asphalt and transmit to the
driver a feeling of safety and confidence in the forecarriage.
[0124] A smaller and lighter suspension may be used given that it
need not withstand flexural loads.
[0125] The reduction of the dimensions of the components of the
suspension also results in a reduction in the mass of the
forecarriage and hence a better handling of the tilting vehicle and
better propensity to lean.
[0126] Also, as seen, the steering axis of the wheels is
considerably moved back in the longitudinal direction with respect
to the rotation pin of the same.
[0127] In this way, a smaller clearance of the back part of the
wheels toward the centerline plane of the vehicle during steering
is obtained. In this way, with the same steering angle of the
wheels, it is possible to use a relatively narrower wheel track, or
transverse distance between the front wheels, without the
respective rear portions of the front wheels interfering with the
frame of the vehicle's forecarriage.
[0128] Consequently, it is possible to use smaller wheel track to
reduce the overall transverse dimensions of the vehicle. The use of
smaller front wheel track contributes to the achievement of an
agile vehicle with a good propensity to lean or tilt.
[0129] In addition, it is possible to position the steering linkage
in the position moved back with respect to the forecarriage and
therefore protected. Moreover, said steering linkage may also be
concealed to an external observer because it is arranged in a
rearward and hidden position.
[0130] Furthermore, due to moving back the steering axis and the
related steering mechanisms/leverages longitudinally, it is
possible to move the mass of the forecarriage back longitudinally
so as to contribute to the so-called centering of the mass in order
to improve the dynamics of the vehicle both in curves and in
acceleration/braking.
[0131] In addition, it is to be noted that the suspended mass of
the forecarriage according to the invention are reduced in order to
improve the ability of the forecarriage to duplicate the roughness
of the road.
[0132] Moreover, it is to be noted that the support structure of
the front wheels is extremely rigid in both the longitudinal and
transverse directions.
[0133] In fact, in the transverse direction, there is provided an
articulated quadrilateral structure that is very robust and allows
the wheels to lean or tilt at the same angle.
[0134] In the longitudinal direction, it should be noted that an
extremely rigid tilting structure is used, given that it provides a
bracket which, on the one hand, is bound to the guide wheel by
appropriate tilting means, and on the other, is in turn bound to
the rigid structure of said transverse quadrilateral. In this way,
longitudinal forces, due to the tilting of the structure, are
discharged onto the rigid structure of the bracket and, via the
latter, onto the articulated quadrilateral.
[0135] In addition, the forecarriage structure of the present
invention is particularly compact so that, advantageously all the
kinematic systems of support, suspension and steering of each wheel
are contained within the space occupied by the rim of the same
wheel. In this way, in addition to obvious aesthetic advantages,
dynamic advantages are also obtained, given that there is a reduced
aerodynamic resistance due to said components being shielded within
each wheel.
[0136] The solution described falls into the case of interconnected
suspensions, given that the balance to a load on a front wheel is
found with an equal load on the paired front wheel; the transfer of
the load takes place through the quadrilateral and therefore
through its inertia, which also involves the whole vehicle and thus
has a lag of a magnitude linked to the inertia itself.
[0137] In practice, the inertia interposed between the paired
wheels acts to bring the solution of interconnected wheels nearer
to one of independent wheels to encourage comfort and to counter
any resonance phenomena that might be triggered on the wheels,
which otherwise would not be dampened.
[0138] Thus, the motor vehicle in accordance with the present
invention is able to guarantee not only a high stability, higher
than that of a two-wheeled motor vehicle due to the presence of two
paired front wheels, but also a remarkable ease of handling and
leaning, typical of a two-wheeled motorcycle.
[0139] Furthermore, as described above, the upper and lower ends of
the uprights of the articulated quadrilateral are placed above and
below the rotation pin of the respective front wheels and not
completely above it, as is the case in the solutions of the known
art. This implies that the stiffness of the connection between each
wheel and the articulated quadrilateral, comprising the suspension,
is an order of magnitude stiffer than the aforementioned solutions
of the prior art, helping to make more remote the possibility that
an alternate resonance of the front wheels may occur due to braking
forces or an asymmetrical impact. Therefore, the present invention
generally contributes to providing a vehicle that is light but also
safe and precise, and transmits to the driver a sense of safety in
the forecarriage, as it does not cause the user to feel vibrations
or shaking in the handlebar.
[0140] A person skilled in the art, in the object of satisfying
contingent and specific requirements, may make numerous
modifications and variations to the solutions described above, all
of which are within the scope of the invention as defined by the
following claims.
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